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nimh tetra @anni @ffice GEORGE l: WASHBURN, OF WORCESTER, MASSACHUSETTS vneem Parmi No. 62,710, ma ammi 1867.

IMPROVEMENT IN STEAM ENGINES.

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TO ALL WHOM IT MAY CONCRN Be it known that I, GEORGE I. WASHBURN, of Worcester, in the county ci" Worcester, and State of Massa chusetts, have invented a new and useful Improvement in Steam Engines', anddohereby declare the following to be a full, clear, and exact description of the same, suihcient to enable one skilled in the art to which the invention appertains to make use of it, reference being had the accompanying drawings, which form a part of this specification, and in which- Figure 1 is a vertical central section through the engine.

Figure 2 Vis a horizontal section on the line xm, iig. l.

Figure 3 is a vertical central section on the line g/ y, rig. y

' Figure ,4 is a vertical section of an engine on the line x x, fig. 5, and diii'ering from iig. 1 in the positions of the cylinders relatively to each other and to the valve-chamber, and showing' also a diierence in the construction oi` the valve.

Figure 5 is a vertical section on 4the line y y, fig. 4.

Figure 6 is a side elevation of the'variable cam which controls the motions of the valve.

Figure 7 is an edge elevation of the same.

This engine hasrwo cylinders, with double acting pistons, to which the steam is admitted through passages guarded by a single valve of peculiar construction; the valve is tubular, in addition to the circular disk, which closes its upper end, and whose projecting periphery ts the wall of the valve-chamber; has two annular disks, one around its lower open end and the other ata point intervening between the two former; steam is constantly admitted to the interior of the valve and passes out through ports in the latter, which are between the upper disk and the one nextv below, the annular space between the two being asteam space, which is brought into correspondence with the passage leading to the cylinders; the annular space between the second disk and the lower one is an exhaust space, which communicates in turn with the cylinders in ,addi-tion tothe above, there is one steam communication below the'valve and `one exhaust communication above it, as will be more fully explained. The valve by the pressure of steam below is kept constantly `pressed upward, so that theroller on the upper end of the valve-rod is maintained in contact withrtho cam on the main shaft, and the cam is so shaped and set upon the shaft as to govern the motions of the valve in the manner desired, the face ci the cam ou the .main shaft has a certain longitudinal variability, so that being shifted along on its axis itmay effect a variable expansion under the inilucnce of the governor-balls. y

In the drawings, .ik C are two cylinders, in which the respective pistons B D reciprocate; the pistons are connected by rods and pitmen to the cranks E F, which are attached to the -inain shaitG, which revolves in bearings supported by the frame H H. Midway of the length of the main shaft is a cam, of peculiar conformation, shown in more particular detail in figs. and 7; this ca-:n is capable-oil adjustment longitudinally of the main shaft, a feather,- z', causing it to rotate therewith.- The face of the cam comes in constant Contact with the friction-roller J, on the upper end of the valve-rod K, which passes through a stuiing-oox into the valvechamber L, Vin which the valve M reciprocates. The valve Misa tube closed at one end by a disk, m, whose projecting iiange is in contact with the walls of the valve-chamber L; around the lower end of the tube of the valve 'it an annular disk, m, and atan intervening point is another disk, m, which', like the disk m,'ts the walls of the chamber. Between the upper disk and tho ring below it are two ports, 0 o, through which steam passesl to the annular space enclosed by said disks; the space between the second disk and the lower one is an exhaust space, as will presently be explained. team passages, a, b, c, d, lead from the valve-chamber to the respective ends `ol" the cylinders, and these passages are alternately induction and eduction passageaas they by the motions of the vulve are broiht into communication 'with the beior by pipe f, or with the exhaust pipo g. The live steam from the boiler is constantly present in pipe f, and presses the valve M upward, so that the roller J` is always in contact with the cam I, and the steam is ready to pass t0 the cyiinzlers as thefvalve is moved for that purpose. i

The operation is an follows; Steam is admitted from the boiler through pipcf, and pas.: s through the valve ivl and the ports o o to the annular space between the disksm m', to the passages L al, which leal respectively to the upper side ofpiston B and the under side of piston D, the 4exhaust steam Vfrom below piston l passing through port to the annular space between disks m/ m, and from them port Il, fig. 23,'50 the exhaust i er the exhaust steam from. above piston esca )es through ort c to the ralve-rimmber above l J. l s Y the valve, and thence by port 7c to the exhaust pipe g. When steam is reversed and the valve rises to the position shown in red lines, the passages whichA were eduction become induction; and conversely, steam being admitted below piston 'B through port L, without passing through the valve, while the steam for the upper side of piston D passes through the valve and ports o to the port ofthe exhaust steam escapes from above the pistonl B through port a, between disks m m, to port h and pipe'g, while this exhaust steam from below piston D lescapes by port el to the saine eduction passage.` It will thus be seenthat while the'disks on the valve open and close the ports, that when the valve M is down the cdnction of steam vfrom above piston D is above the valve and not through it, and when the valve M is raisedtheinduction of steam below piston B is below the valveand not through it; with these exceptions the induction of steam is through the valve and portsro, and thecduotion of steam is around the valve between the annular disks m m. I have mentioned that the-1notionsof the valve a'rc controlled by the constant pressure of steam belowand by the downward pressure of .the cam, which is eccentric, a revolution of the cam corresponding to a complete round of motions of the pistons in their cylinders. The variations in the radiusiof the perimeter ofthe cam answer to the desired verticallpositions of the valve M; by a proper conformation of the face of the cam it may be made to exert avvariable action on the valve asit is slipped longitudinally on the shaft to bring a different portion of its periphery in contact with the friction-roller on the upper end of the vaivcijod. i

Diagrams 1 and 2 will illustrate the construction of the eccentric.

Diagram 1 shows an eccentric, arranged to make a quick cut-off, the circula; portions representingl the cut-off middle position of the valve, atv which it rests, excepting at theropposite points 5 G, which represent, respectively, the upper and lower positions of the valve admitting steam below-and above the piston in a given cylinder. At these points the valves make a Asudden motion up and down, respectively, opening for a short time the Steam induction port of a given cylinder. l

v i Diagram 2 shows an eccentric arranged for full steam, the valve resting in its lower position, while the surface 1 is in contact with the valverod, and in its upper position, when the surface2 is, under like contacting circumstances, making its up and down motion by the inclinedl planes 3 3.

New, if on an eccentric with a wide face, such as is represented in figs. 6 and 7, one edge be made to correspond with dia-gram 1 and the other edge with diagram 2, by'shifting the eccentric longitudinally on its shaft so that the friction-roller on the upper end of the valve-rod may be in contact with one or the other of 4these portions of the 'surface of the cam, a variability of steam induction may be attained-4a quick cut-off or full steam.

The respective edges of the cam being lthusy shaped, it remains to unite the two by oblique lines, one of which is indicated by 7, (see figs. 6 and 7,) thus the position of thc valve indicated bythe radius 1 being maintained for about hali a revolution of the cam, i'n iig. 2, and but momentarily at 6, in fig` 1, by an oblique line uniting the two the time during which the valve shall be in the lower position due to this radius, 1 or 6, may be varied from the quick cut-off of b', iig. 1, to the full steam of 1, fig. 2. The same is true of the counterpart depression 5 of tig. 1, and thc curve ot' small radius 2, iig. 2, when the valve is at its highestand the cylinder receives its steam below the piston. To repeat, one edge of the cam gives one motion-'and the other edge the other motion. The face of the cam is dressed oil` from one edge to the other, so as to give all the mediums these two extreme effects. In regard to the arrangement of the disks and p'orts so as to'permit la cut-cff'of the steam without closing the exhaust simultaneously therewith, may be accomplishedy by making a variation in the respective distances between the disks and the ports', so that the steam would be cnt oii' before the exhaust port' was entirelyT closed,`the disks being brought a little nearer together; so that when one covers a steam-induction port the other does not quite cover an exhaust port; or the distances between, the disks may be a little greater than that between ports, as thecase requiresA n, tige. 4 and 5 is shown a modification ofthe arrangement, diii'eying in two respects from that shown in lfigs. 1 and 2, 'namelyzl First. The cylinders in igs. 4 5`are arranged upon diii'crcnt levels, which shortensthe steam passages from them to the valve-chamber, while the length of the latten is increased.

Second. 'lhe valve, instead ofc-being hollow, with three disks at different heights fitting the walls 'of the chamber, consists oi' a stem with three disks upon it; andthe stem is admitted atl two points into the valvechamber between the upper and middle disk and below the lower one. Thus, the space between the upper and middle disk and the space beloiv the lower disk are-'constant steam-spaces, and the spafce abovc'thc upper disk and that between the middle and lower disk are constant exhaust-spaces. The said-v steam and exhaustspaces being consecutively brought into correspondence with the ports leading to the respective ends of the cylinders. y

1n thc drawings, figs. 4 5, S is the steam pipe. Proceeding-from the boiler t t are tWo'stcam-ports leading to the valvefclntmber. a l) are the ports to the upper and lower ends, respectively, of the cylinder A; and c d are theportsleading -t'o the upper and lower ends, respectively, of'the cylinder C. h [L are' ports leading from the valve-chamber to the exhaust pipe-g. With the exceptions referred to, the action of the, steam is similar to that described in iigs. 1 2, and the action on the-pistons isidentical. y

Having described my invention, what 1 claim thereinas new, and desire to secure by Letters Patent, is

1. The arrangement of the cylinders A C, with their double-acting pistons B D, and valve with three disks reciprocating in the chamber between the cylinders and controlling the ports, substantially as described.

claim a'steani-valve, when arranged to bev operated by a pressure from below and an eccentric above, substantially as described.l

GEORGE I. WASHBURN.

Witn esses:

S. l?. Mouse, EDWARD MELLEN. 

